The present invention relates to a method and apparatus for the injection molding of unsaturated polyester resin masses, possibly reinforced with fibers.
The transformation of reinforced, unsaturated polyester resin compounds for the production of molded articles is generally carried out by the introduction of the molding mass which is almost at ambient temperature, generally between 140.degree. and 180.degree.. The time necessary for the material to reach the correct polymerization temperature greatly limits the productivity of the molding plant and may sometimes have an adverse effect on the homogeneity of the results.
In injection molding in which the material is introduced into the die through a ramming unit, the preheating of the material is particularly problematical since there is a risk that the material will polymerize before injection.